Ring‐Opening Reactions of Cyclopropenedicarboxylates with Organolithiums and Organozincs

Ring‐opening reactions of cyclopropenedicarboxylates with organolithiums and organozincs have been studied. Organolithiums and dialkyl‐ or diphenylzincs afforded a series of 1‐alkenyl malonates with attack occurring by the organic group from the organometallic reagent at the less substituted sp 2 ‐hybridized carbon of the cyclopropene moiety. Mechanistic studies proved both anion and dianion intermediates are involved in the reactions with organolithiums. Phenylcyclopropenedicarboxylate and phenylzinc bromide underwent a ring‐opening dimerization to afford a 1,4‐enyne product.